All the talk in your typical Senate analysis this year has assumed Republican Mike Castle will beat Democrat Chris Coons in the Delaware Senate race, but the fact is there’s still a GOP primary in progress.

It’s forgivable to forget about that primary when polling of the primary is scarce, and PPP and Rasmussen hold Coons under 40, but let’s extrapolate from the PPP poll to the primary.

Some would question the handicapping of a Republican primary with of a poll from PPP (a firm aligned with Democrats) and commissioned by Daily Kos, which is fair, but we can keep their biases in mind for the worst case. And if you want Chris Coons to win, what do you want to see? You want a difficult primary. You want money spent, allegations hurled, and feelings hurt. Any bias here is going to be against the frontrunner and for the underdog challenger.

That challenger is, of course, Christine O’Donnell. Top lines involving her have been mixed: some say she can beat Chris Coons, others say she can’t. That’s not what I’m looking for today though. I’m looking at how Republicans are evaluating her candidacy, and for that I’m going to delve into the PPP crosstabs.

First we look at overall approval figures. Delaware registered Republicans (this is not a likely voter poll) favor Castle 60/25 for +35, but only favor O’Donnell 34-29 +5. Nearly a majority of Delaware Conservatives favor Castle 46/39 for +5, while those conservatives favor O’Donnell 37/23 for +14. And for one more split: McCain voters favor Castle 54/31 or +23, while they favor O’Donnell only 32/29 or +3. It seems to me that O’Donnell is only better liked than Castle if only conservatives vote in the primary, while the rest of the GOP stays home.

“Ah!” the O’Donnell supporters will cry, “But Mike Castle is out of step with the Republican Party!” though he pretty much had to be, given that his House district tilts so far left that most analysts gave it up for the Democrats as soon as he announced he was moving on to the Senate. “He won’t excite the base in the general!” Well, let’s look at how O’Donnell does in the general. In the general among conservatives, Castle beats Coons 67-13, while O’Donnell beats Coons 69-13. Among McCain voters, Castle wins 75-10 and O’Donnell wins 71-13. Among Republicans, Castle wins 75-12 and O’Donnell wins 67-17.

I just see no evidence that Castle is disliked enough by Delaware Republicans, Conservatives, and McCain voters for an O’Donnell candidacy to catch on like those of Marco Rubio, Mike Lee, or Pat Toomey. Christine O’Donnell’s core challenge is to give Delaware Republicans who like Mike Castle a reason to vote against him anyway.